1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a chip-on-glass type liquid crystal display device and the fabricating method thereof that is adaptive for preventing a joint defect of an anisotropic conductive film.
2. Description of the Related Art
A liquid crystal display device controls the light transmittance of a liquid crystal in use of an electric field, thereby displaying a picture. To this end, the liquid crystal display device includes a liquid crystal display panel where liquid crystal cells are arranged in a matrix pattern; and a drive circuit for driving the liquid crystal display panel.
In the liquid crystal display panel, gate lines and data lines are arranged to cross each other, and liquid crystal cells are located in areas provided by the crossing of the gate lines and the data lines.
The drive circuit includes a gate driver for driving the gate lines and a data driver for driving the data lines.
Each of the gate driver and the data driver includes a plurality of drive integrated circuits (hereinafter, referred to as “IC”). Each of the data drive IC and the gate drive IC is mounted on the liquid crystal display panel by a chip-on-glass (hereinafter, referred to as “COG”) method in a small and medium size liquid crystal display device, as in FIG. 1.
The COG process is explained centering on the data drive IC as follows.
Referring to FIGS. 1 and 2, a lower glass substrate 9 includes a data line 4; a data link 3 connected to the data line 4; a data pad 2 formed at an end of the data link 3; an FPC connection line 6; and first and second FPC connection pads 5, 7 formed at both ends of the FPC connection line 6. The lower glass substrate 9 is bonded with an upper glass substrate 8, in which a color filter and a black matrix are formed, in use of a sealant.
The COG process includes a process of temporarily pressing an anisotropic conductive film (hereinafter, referred to as “ACF”) 1 onto the lower glass substrate 9, as in FIG. 1; and a process of permanently pressing the data drive IC onto the ACF 1 in use of a heat pressure process, as in FIG. 2.
The temporary pressure process joins the ACF 1 to a non-display surface 10 the edge of the lower glass substrate 9 so as to sufficiently cover the data pads 2, parts of the gate links 3, the first FPC connection pads 5 and parts of the FPC connection lines 6, which are disposed in the non-display surface 10 of the edge of the lower glass substrate 9 that are not overlapped with the upper glass substrate 8, and then temporarily pressing thereonto, as in FIG. 1. The ACF 1 is covered by a protection sheet 1a. 
The permanent pressure process peels off the protection sheet 1a from the ACF 1 after cutting the ACF 1 covered by the protection sheet 1a, as in FIG. 1, and then aligns output bumps of the data drive IC 11 to the data pads 2 and aligns input bumps of the data drive IC 11 to the first FPC connection pads 5 as in FIG. 2. And, the permanent pressure process applies heat to the ACF 1 by a heat pressure process using a bonding head and simultaneously press the data drive IC 11 onto the lower glass substrate 9, thereby completely bonding the data drive IC 11 onto the lower glass substrate 9.
And, the ACF 1 has a characteristic of being badly joined with glass, thus the ACF 1 is peeled off along with the protection sheet 1a, as in FIG. 3, when the protection sheet 1a is peeled off from the ACF 1 which is joined to the lower glass substrate 9 in the temporary pressure process. And, as a result thereof, there is generated a joint defect of the data drive IC because of being stuck to other part than the joint part of the data drive IC.